Blower pipe, blowing device, and image forming apparatus

ABSTRACT

A blower pipe includes an inlet port, an outlet port, a flow path that connects the inlet port and the outlet port to cause air to flow therethrough and that are divided by a partition wall, and plural flow control members that are respectively provided in different parts in an air flow direction in each of divided passage spaces that are divided by the partition wall and that control the flow of the air, wherein the inlet port and the outlet port are constituted by plural opening portions, respectively, the plural opening portions that constitute the outlet port have elongated opening shapes divided by the partition wall, and a flow control member of the plural flow control members closest to the inlet port is provided in the vicinity of the bent portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 fromJapanese Patent Application No. 2012-272359 filed Dec. 13, 2012.

BACKGROUND

(i) Technical Field

The present invention relates to a blower pipe, a blowing device, and animage forming apparatus.

(ii) Related Art

In image forming apparatuses that form an image constituted with adeveloper on a recording sheet, for example, there is an image formingapparatus using a corona discharger that performs corona discharge inthe process of charging a latent image holding member, such as aphotoconductor or the process of neutralization, the process oftransferring an unfixed image to the recording sheet, or the like.

Additionally, in the corona discharger, in order to prevent unnecessarysubstances, such as paper debris or a discharge product, from adheringto component parts, such as a discharge wire or a grid electrode, ablowing device that blows air against component parts may be provided.The blowing device in this case is generally constituted by a blowerthat sends air, and a duct (blower pipe) that guides and sends out theair sent from the blower to a target structure, such as a coronadischarger.

In the related art, improvements for enabling air to be uniformly blownin the longitudinal direction of the component parts, such as adischarge wire, are variously performed on the blowing device or thelike. Particularly, for a blowing device or the like, there is proposeda blowing device that does not adopt a configuration, in which the shapeof a passage space of a duct through which air is caused to flow isformed in a special shape, or a configuration, in which a straighteningvane or the like that adjusts a direction in which air flows isinstalled in the passage space of the duct, or the like, but the blowingdevice adopts separate configurations as illustrated below.

SUMMARY

According to an aspect of the invention, there is provided a blower pipeincluding: an inlet port that takes in air; an outlet port that has anelongated opening shape that is parallel to a portion of a elongatedtarget structure in a longitudinal direction and that is arranged so asto face the portion of the elongated target structure in thelongitudinal direction against which the air taken in from the inletport is to be blown and is different from the opening shape of the inletport; a flow path that connects the inlet port and the outlet port tocause air to flow therethrough and that are divided by a partition wallthat is continuously provided from the inlet port to the outlet port andthat has a bent portion which bends flow direction substantially at aright angle; and plural flow control members that are respectivelyprovided in different parts in an air flow direction in each of dividedpassage spaces that are divided by the partition wall and that controlthe flow of the air, wherein the inlet port and the outlet port areconstituted by plural opening portions that are divided by the partitionwall, respectively, wherein the plural opening portions that constitutethe outlet port have elongated opening shapes that are divided by thepartition wall in a state where the elongated opening shape of theoutlet port is parallel to the longitudinal direction of the targetstructure, and wherein a flow control member of the plural flow controlmembers closest to the inlet port is provided in the vicinity of thebent portion, which makes a portion of each of the flow path narrowerthan other portion of each of the flow path and makes an elongated gapextending in the longitudinal direction to pass air.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described indetail based on the following figures, wherein:

FIG. 1 is an explanatory view showing the outline of a blower pipe and ablowing device and an image forming apparatus using the same related toExemplary Embodiment 1 or the like;

FIG. 2 is a schematic perspective view showing a charging deviceincluding a corona discharger provided in the image forming apparatus ofFIG. 1;

FIG. 3 is a schematic perspective view showing the outline of a blowerpipe and a blowing device to be applied to the charging device of FIG.2;

FIG. 4 is a perspective view showing the blower duct of FIG. 3 that ispartially seen through;

FIG. 5 is a cross-sectional view along line Q-Q of the blowing device(blower duct) of FIG. 3;

FIG. 6 is a schematic view showing a state when the blowing device ofFIG. 3 is seen from above;

FIG. 7 is a view showing a state when a portion of an outlet port in theblower duct of FIG. 4 is seen from below;

FIG. 8 is a cross-sectional view along line Q-Q of the blower duct ofFIG. 4;

FIG. 9 is an explanatory view showing the operating state or the like ofthe blowing device related to Exemplary Embodiment 1;

FIG. 10 is a graph chart showing the results of an evaluation testregarding the performance characteristics of the blowing device (blowerduct) related to Exemplary Embodiment 1;

FIG. 11 is a streamline view showing the results when the blowing stateof air of the blowing device (blower duct) related to ExemplaryEmbodiment 1 to the charging device is simulated;

FIG. 12 is a cross-sectional view showing a configuration example of ablower duct in a blowing device related to Exemplary Embodiment 2;

FIG. 13 is a cross-sectional view showing another configuration exampleof the blower duct in the blowing device related to Exemplary Embodiment2;

FIGS. 14A and 14B show the results when the blowing state of air of theblowing device (two sorts of blower ducts) related to ExemplaryEmbodiment 2 to the charging device is simulated, FIG. 14A is astreamline view showing the results when the blower duct of theconfiguration example shown in FIG. 12 is applied, and FIG. 14B is astreamline view showing the results when the blower duct of theconfiguration example shown in FIG. 13 is applied;

FIG. 15 is a cross-sectional view showing a blower duct in a blowingdevice related to Exemplary Embodiment 3;

FIG. 16 is a streamline view showing the results when the blowing stateof air of the blowing device (blower duct) related to ExemplaryEmbodiment 3 to the charging device is simulated;

FIG. 17 is a cross-sectional view showing a blower duct in a blowingdevice related to Exemplary Embodiment 4;

FIG. 18 is a view showing a state when a portion of an outlet port inthe blower duct of FIG. 17 is seen from below;

FIGS. 19A to 19D are top explanatory views showing various form examplesof the blower duct;

FIG. 20 is a cross-sectional explanatory view showing the configurationor the like of main portions of a blower duct of a comparative example;

FIGS. 21A and 21B show an evaluation test regarding the performancecharacteristics of the blower duct of FIG. 20, FIG. 21A is a graph chartshowing the results of the evaluation test regarding the performancecharacteristics when a certain air volume of air is taken into theblower duct, and FIG. 21B is a graph chart showing the results of theevaluation test when a larger air volume air than that of the case ofFIG. 21A is taken in; and

FIG. 22 is a streamline view showing the results when the blowing stateof air of the blowing device to which the blower duct of the comparativeexample is applied, to the charging device, is simulated.

DETAILED DESCRIPTION

Hereinafter, the modes (simply referred to as “exemplary embodiments”)for carrying out the invention will be described with reference to theaccompanying drawings.

Exemplary Embodiment 1

FIGS. 1 to 3 show a blower pipe related to Exemplary Embodiment 1 and ablowing device and an image forming apparatus using the same. FIG. 1shows the outline of the image forming apparatus, FIG. 2 shows acharging device as an example of an elongated target structure on whichair is to be blasted by the blower pipe or the blowing device, in theimage forming apparatus, and FIG. 3 shows the outline of the blower ductor the blowing device.

In the image forming apparatus 1, as shown in FIG. 1, an image formingunit 20 that forms a toner image constituted by a toner as a developerto transfer the toner to a sheet 9 as an example of a recordingmaterial, a sheet feeder 30 that accommodates and transports sheets 9 tobe supplied to the image forming unit 20, and a fixing device 35 thatfixes the toner image formed by the image forming unit 20 on a sheet 9are installed in an internal space of a housing 10 constituted by asupport frame, an outer cover, or the like. Although only one imageforming unit 20 is illustrated in Exemplary Embodiment 1, aconfiguration in which the image forming unit is constituted by pluralimage forming units may be adopted.

The above image forming unit 20 is configured, for example utilizing awell-known electrophotographic system, and is mainly constituted by aphotoconductor drum 21 that is rotationally driven in the direction (theclockwise direction in FIG. 1) indicated by an arrow A, a chargingdevice 4 that charges a peripheral surface that is an image formingregion of the photoconductor drum 21 with a required potential, anexposure device 23 that irradiates the surface of the photoconductordrum 21 after charging with light (dotted line with an arrow) based onimage information (signal) input from the outside to thereby form anelectrostatic latent image with a potential difference, a developingdevice 24 that develops the electrostatic latent image as a toner imagewith a toner, a transfer device 25 that transfers the toner image to asheet 9, and a cleaning device 26 that removes the toner or the likethat remains on the surface of the photoconductor drum 21 aftertransfer.

Among these, a corona discharger is used as the charging device 4. Thecharging device 4 including this corona discharger is constituted by aso-called scorotron type corona discharger, as shown in FIG. 2 or thelike.

That is, the charging device 4 includes a shielding case 40 as anexample of a surrounding member with an external shape having an oblongtop plate 40 a, and lateral portions 40 b and 40 c that hang downwardfrom long side portions extending along the longitudinal direction B ofthe top plate 40 a, two end supports (not shown) that are respectivelyattached to both ends (short side portions) of the shielding case 40 inthe longitudinal direction B, two corona discharge wires 41A and 41Bthat are attached so as to be stretched in a state where the wires arepresent within an elongated internal space extending along thelongitudinal direction B of the shielding case 40 and are substantiallyparallel to each other, between these two end supports, and a perforatedgrid electrode (electric field adjustment plate) 42 that is attached toa lower opening portion 44 for discharge of the shielding case 40 in astate where the plate substantially covers the lower opening portion 44and is present between the corona discharge wires 41 and the peripheralsurface of the photoconductor drum 21. Reference numeral 40 d shown inFIG. 4 or the like represents a boundary plate that partitions the spacewhere the two corona discharge wires 41A and 41B are arranged, along thelongitudinal direction B of the shielding case 40. The opening shape ofthe lower opening portion 44 becomes oblong.

Additionally, the charging device 4 is arranged such that the two coronadischarge wires 41A and 41B are present at least so as to face an imageforming target region along the direction of a rotational axis of thephotoconductor drum 21 in a state where the wires face each other at apredetermined interval (for example, discharge gap) from the peripheralsurface of the photoconductor drum 21. Additionally, the charging device4 is adapted such that charging voltages are respectively applied to thedischarge wires 41A and 41B (between the wires and the photoconductordrum 21) from a power unit (not shown) when an image is formed.

Moreover, with the use of the charging device 4, substances (unnecessarysubstances), such as paper debris of a sheet 9, a discharge productgenerated by corona discharge, and external additives of toner, adhereto the corona discharge wires 41 or the grid electrode 42, and arecontaminated, and the corona discharge is no longer sufficiently oruniformly performed. As a result, charging defects, such as unevencharging, may occur. For this reason, in order to prevent or keepunnecessary substances from adhering to the discharge wires 41 and thegrid electrode 42, a blowing device 5 for blasting air against twointernal spaces S1 and S2 (spaces where the discharge wires 41A and 41Bare present, respectively) partitioned by the boundary plate 40 d of theshielding case 40 is provided together at the charging device 4.Additionally, the top plate 40 a of the shielding case 40 of thecharging device 4 is formed with an opening 43 for taking in the airfrom the blowing device 5. The opening 43 is formed so that the openingshape thereof is an elongated oblong shape. The blowing device 5 will bedescribed below in detail.

The sheet feeder 30 includes a sheet accommodation member 31 of a traytype, a cassette type, or the like that accommodates plural sheets 9including a required size, required kind, or the like to be used forformation of an image, in a stacked state, and a delivery device 32 thatdelivers the sheets 9 accommodated in the sheet accommodation member 31one by one toward a transporting path. If the timing for sheet feedingcomes, the sheets 9 are delivered one by one. Plural sheet accommodationmembers 31 are provided according to utilization modes. A one-dot chainline with an arrow in FIG. 1 shows a transporting path which a sheet 9is mainly transported along and passes through. This transporting pathfor sheets is constituted by plural sheet transporting roll pairs 33 aand 33 b, transporting guide members (not shown), or the like.

The fixing device 35 includes, inside a housing 36 formed with anintroduction port and an ejection port through which a sheet 9 passes, aroll-shaped or belt-shaped heating rotary member 37 of which the surfacetemperature is heated to and maintained at a required temperature by aheating unit, and a roll-shaped or belt-shaped pressurizing rotarymember 38 that is rotationally driven in contact with the heating rotarymember 37 at a required pressure so as to extend substantially along thedirection of the rotational axis of the heating rotary member. Thefixing device 35 performs fixing by allowing a sheet 9 after a tonerimage is transferred to be introduced into and pass through a contactportion (fixing processing section) that is formed as the heating rotarymember 37 and the pressurizing rotary member 38 come into contact witheach other.

Image formation by the image forming apparatus 1 is performed asfollows. Here, a basic image forming operation when an image is formedon one surface of a sheet 9 will be described as a representativeexample.

In the image forming apparatus 1, if the control device or the likereceives a start command for an image forming operation, in the imageforming unit 20, the peripheral surface of the photoconductor drum 21that starts to rotate is charged with predetermined polarity andpotential by the charging device 4. At this time, in the charging device4, corona discharge is generated in a state where charging voltages areapplied to the two corona discharge wires 41A and 41B, respectively, andan electric field is formed between each of the discharge wires 41A and41B and the peripheral surface of the photoconductor drum 21, andthereby, the peripheral surface of the photoconductor drum 21 is chargedwith a required potential. In this case, the charging potential of thephotoconductor drum 21 is adjusted by the grid electrode 42.

Subsequently, an electrostatic latent image, which is configured with arequired potential difference as exposure is performed on the basis ofimage information from the exposure device 23, is formed on theperipheral surface of the charged photoconductor drum 21. Thereafter,when the electrostatic latent image formed on the photoconductor drum 21passes through the developing device 24, the electrostatic latent imageis developed with a toner that is supplied from the developing roll 24 aand charged with a required polarity, and is visualized as a tonerimage.

Next, if the toner image formed on the photoconductor drum 21 istransported to a transfer position that faces the transfer device 25 bythe rotation of the photoconductor drum 21, the toner image istransferred by the transfer device 25 to a sheet 9 to be suppliedthrough the transporting path from the sheet feeder 30 according to thistiming. The peripheral surface of each photoconductor drum 21 after thistransfer is cleaned by the cleaning device 26.

Subsequently, the sheet 9 to which the toner image is transferred in theimage forming unit 2 is transported so as to be introduced into thefixing device 35 after being peeled off from the photoreceptor drum 21,is heated under pressurization when passing through the contact portionbetween the heating rotary member 37 and the pressurizing rotary member38 in the fixing device 35, and is fixed on the sheet 9. The sheet 9after this fixing is completed is ejected from the fixing device 35, andis transported and accommodated in an ejected sheet accommodationsection (not shown) or the like that is formed, for example, outside thehousing 10.

From the above, a monochrome image constituted by a single-color toneris formed on one surface of one sheet 9, and the basic image formingoperation is completed. When there is an instruction for the imageforming operation for plural sheets, a series of operations as describedabove are similarly repeated by the number of sheets.

Next, the blowing device 5 will be described.

As shown in FIG. 1, 3, or the like, the blowing device 5 includes ablower 50 that has a rotary fan that sends air, and a blower duct 51that takes in the air sent from the blower 50 and guides and blows outthe air to the charging device 4 that is an object to be blown.

As the blower 50, for example, an axial flow type blower fan is used andthe driving thereof is controlled so as to send a required volume ofair. Additionally, the blower duct 51, as shown in FIGS. 3 to 6, isformed in a shape having an inlet port 52 that takes in the air sentfrom the blower 50, an outlet port 53 that is arranged in a state wherethe outlet port faces the portion (the top plate 40 a of the shieldingcase 40), in the longitudinal direction B, of the elongated chargingdevice 4 against which the air taken in from the inlet port 52 is to beblown, and emits the air so as to flow along a direction orthogonal tothe longitudinal direction B, and a flow path (body portion) 54 formedwith a passage space TS for connecting the inlet port 52 and the outletport 53 to cause air to flow therethrough.

The flow path 54 of the blower duct 51 is constituted by an introductionflow path 54A, a first bent flow path 54B, and a second bent flow path54C as will be described below in detail. The introduction flow path 54Ahas one end portion provided with the inlet port 52 opened and has theother end portion closed, and the overall flow path is constituted by anangular-tube-shaped flow path formed so as to extend along thelongitudinal direction B of the charging device 4. The first bent flowpath 54B is an angular-tube-shaped bent flow path formed so as to extendafter being bent substantially at a right angle to a substantiallyhorizontal direction (direction substantially parallel to the coordinateaxis X) in a state where the width of the passage space is increasedfrom a part near the other end portion of the introduction flow path54A. The second bent flow path 54C is a second bent flow path formed soas to extend after being finally bent in a downwardly perpendiculardirection (direction substantially parallel to the coordinate axis Y) soas to move close to the charging device 4 in a state where the width ofthe passage space remains equal from one end portion of the first bentflow path 54B. Among these, the widths (dimensions along thelongitudinal direction B) of both the passage spaces TS of the firstbent flow path 54B and the second bent flow path 54C are set to almostthe same dimension.

The overall opening shape (the shape of the inlet port before a passagespace is divided by a partition wall 55 to be described below) of theinlet port 52 of the blower duct 51 is formed so as to become, forexample, a substantially square shape. A connection duct 58 forconnecting between the blower duct 52 and the blower 50 to send the airgenerated by the blower 50 to the inlet port 52 of the blower duct 51 isattached between both the blower duct and the blower (FIG. 3).

Additionally, the outlet port 53 of the blower duct 51 is formed so thatthe opening shape (the shape of the outlet port before a passage spaceis divided by the partition wall 55 to be described below) thereof is anelongated shape (for example, oblong shape) parallel to the portion ofthe charging device 4 in the longitudinal direction B. The outlet port53 is actually formed at a termination end of the second bent flow path54C of the blower duct 51. For this reason, the blower duct 51 has therelationship where the inlet port 52 and the outlet port 53 are formedin different opening shapes. In addition, even in a case where the inletport 52 and the outlet port 53 have the same type of shape, a case wherethe inlet port and the outlet port are formed so as to have differentopening areas (when the inlet port and outlet port have a similar shape)is included in the relationship where the inlet port and the outlet portare formed in different opening shapes.

Here, in the blower duct 51 in which the inlet port 52 and the outletport 53 are formed in different opening shapes in this way, the portionin which the cross-sectional shape of the passage space TS is changedmidway is present in the flow path 54 that connects between the inletport 52 and the outlet port 53. Incidentally, in the blower duct 51, thecross-sectional shape of the passage space TS having a substantiallysquare shape, of the introduction flow path 54A is changed to thecross-sectional shape of the passage space TS including an oblong shapethat widens only in the horizontal direction (no change in height) inthe first bent flow path 54B. In other words, the cross-sectional shapeof the passage space TS of the introduction flow path 54A is thecross-sectional shape of the passage space TS that abruptly becomes widein the first bent flow path 54B.

Additionally, in the case of the blower duct 51 in which such a portionin which the cross-sectional shape of the passage space TS changes ispresent, disturbance, such as flaking or vortex, occurs in the flow ofair in the portion in which the cross-sectional shape of the blower ductchanges. For this reason, even if air with a uniform wind speed is takenfrom the inlet port 52, the wind speed of the air that comes out fromthe outlet port 53 tends to become non-uniform. In addition, thetendency that the wind speed of the air that comes out from the outletport becomes non-uniform in this way occurs almost similarly even in acase where the direction in which the air in the blower duct 51 iscaused to flow (proceed) changes irrespective of the presence of achange in the cross-sectional shape of the passage space TS.

FIGS. 19A to 19C show representative examples 510A to 510C of the blowerduct in which the inlet port 52 and the outlet port 53 are formed indifferent opening shapes. In the drawings, respective states of the windspeed of air taken into the inlet port 52 and the wind speed of air thatcomes out from the outlet port 53 in the respective ducts 510 are shownby the lengths of arrows, respectively. FIGS. 19A to 19D show therespective blower ducts 510 seen from the top face thereof.Additionally, in the drawings, cases where the lengths of the arrows arethe same show that the wind speeds are the same, and cases where thelengths of the arrows are different show that the wind speeds aredifferent. Moreover, dotted lines in the drawings show (side wallportions that form) the passage spaces of the respective ducts.Incidentally, the blower ducts 510B and 510D are also configurationexamples in which the direction in which air is caused to flow ischanged midway, and at least one of the cross-sectional shape andcross-sectional area of the passage spaces is changed. In addition, theblower duct 510D shown in FIG. 19D is a configuration example in whichthe inlet port 52 and the outlet port 53 are formed in the same openingshape (and the same opening area), and is a duct in which only thedirection in which air is caused to flow is changed midway.

Thus, in the blower duct 51 of the blowing device 5, as shown in FIGS. 3to 8 or the like, the flow path 54 is constituted as the flow path 54that has two passage spaces TS1 and TS2 divided so as to have almost thesame space shape by a plate-shaped partition wall 55 provided in a statewhere the passage space TS is continuous from the inlet port 52 to theoutlet port 53, and, two flow control members 61 and 62 that suppressthe flow of air are provided in different parts in the direction inwhich the air of each of the divided passage spaces TS1 and TS2 of theflow path 64 is caused to flow.

One flow control member 61 is an upstream flow control member providedin a midway part in the air flow direction, of each passage space TS1 orTS2 of the flow path 54. Additionally, the other flow control member 62is a most downstream flow control member provided on the outlet port 53side of each passage space TS1 or TS2 of the flow path 54. Referencenumeral 56 in FIG. 3 or the like represents an attachment auxiliaryportion formed in a desired shape for fixing the blower duct 51 to itsattachment place.

In the blower duct 51, the inlet port 52 and the outlet port 53 aredivided by the partition wall 55 of the flow path 54, respectively, andare constituted by two opening portions, respectively. That is, theinlet port 52 is constituted by two opening portions 52A and 52B, andthe outlet port 53 is constituted by two opening portions 53A and 53B.

The opening portions 52A and 52B that constitute the inlet port 52 inExemplary Embodiment 1 are provided so that an opening portion having anoriginal square shape, of the inlet port 52 is substantially equallydivided into two that are parted in the vertical direction by thepartition wall 55, and both the opening shapes thereof are formed in ashort oblong shape. Additionally, the opening portion 52A and theopening portion 52B that constitute the outlet port 53 are substantiallyequally divided into two by the partition wall 55 so that an originalelongated oblong opening portion of the outlet port 53 is parallel alongthe longitudinal direction B of the charging device 4, and both theopening shapes thereof are formed in a subdivided elongated oblongshape. Even in this case, since the opening shape of the openingportions 52A and 52B that constitute the inlet port 52 and the openingshape of the two opening portions 53A and 53B that constitute the outletport 53 are a short oblong shape and an elongated oblong shape,respectively, as described above, these opening portions remain in therelationship of different opening shapes.

Additionally, the upstream flow control member 61 is provided at asubstantially intermediate position in the direction in which air iscaused to flow in each passage space TS1 or TS2 of the first bent flowpath 54B. The upstream flow control member 61 is configured so as to cutoff a portion of each passage space TS1 or TS2 in such a manner to crosseach passage space TS1 or TS2 of the first bent flow path 54B along thedirection parallel to the longitudinal direction (the same direction asthe longitudinal direction B of the charging device 4) of the openingshape of each opening portion 53A or 53B of the outlet port 53, and soas to have a gap 63 in an elongated shape that extends in the crossingdirection.

The upstream flow control member 61 in Exemplary Embodiment 1 isconfigured by causing a plate-shaped partition member 64 to be presentwithin each passage space TS1 or TS2 of the bent flow path 54B withoutchanging the external shape of the first bent flow path 54B. That is,the upstream flow control member 61 is arranged so that the partitionmember 64 closes an upper space portion in each passage space TS1 or TS2of the first bent flow path 54B, and a lower end 64 a of the partitionmember has a required interval H with respect to the bottom (inner wall)of the passage space TS. This forms a structure where the gap 63 ispresent in a lower portion of each passage space TS1 or TS2. Thepartition member 64 is formed by being molded integrally with the duct51 from the same material as the duct or is formed from a materialseparate from the duct 51.

The height H, path length M, and width (length along the longitudinaldirection B) W of the gap 63 are selected and set from the viewpoint ofmaking the wind speed of air that has flowed into the first bent flowpath 54B from the introduction flow path 54A as uniform as possible, andare set in consideration of the dimensions (capacity) of the duct 51,and the flow rate per unit time of air caused to flow to the duct 51,the charging device 4, or the like. For example, the height H of the gap63 may be set to the dimension uniformly or partially changed from theabove viewpoint or the like without being limited to a case where thedimension is set to the same dimension in the width direction. InExemplary Embodiment 1, as for the height H of the gap 63, aconfiguration in which a height H1 in an end portion near the inlet port52 and a height H2 in an end portion apart from the inlet port 52 areset to almost the same value (that is, a case where the heights are setto the same dimension in the width direction of the gap 63) is shown.

On the other hand, in the most downstream flow control member 62, theopening portion 53A or 53B of the outlet port 53 of each passage spaceTS1 or TS2 is formed in a shape having a smaller cross-sectional areathan the cross-sectional area of each passage space TS1 or TS2. Theopening shape of the opening portion 53A or 53B in Exemplary Embodiment1 is formed in an elongated oblong shape in which only the length (sidesthat are present at both ends in the longitudinal direction) of theshort sides of the elongated oblong shape are made shorter than theshort sides of the oblong cross-sectional shape of each passage spaceTS1 or TS2, and the length of the long sides thereof is the same as thelong sides of the oblong cross-sectional shape of each passage space TS1or TS2. The opening portions 53A and 53B at this time face the internalspaces S1 and S2, respectively, which are divided into two by theboundary plate 40 d, in a corresponding manner through the top openingportion 32 of the shielding case 40 of the charging device 4 (FIG. 5).

Additionally, in the most downstream flow control member 62, the openingportion 53A or 53B of the outlet port 53 of each passage space TS1 orTS2 is also configured as the shape of a terminal portion of a passagespace TS1 e or TS2 e that guides air so as to be emitted in a requireddirection and determines the emission direction of air.

In Exemplary Embodiment 1, the passage space TS1 e or TS2 e thatdetermine the emission direction of air, are provided in a part of aform that extends substantially in the shape of a straight line on thedownstream side of the second bent flow path 54C. That is, the passagespace TS1 e or TS2 e, as shown in FIG. 8 or the like, is formed in sucha shape such that the overall passage thereof has a smallercross-sectional area than the cross-sectional area of each passage spaceTS1 or TS2, and is set so that the air flow direction on the downstreamside of the passage is a direction that inclines inward with respect toeach extension line EL1 or EL2 along the outside inner wall surface ofthe part of each passage space TS1 or TS2 of a form that extendsubstantially in the shape of a straight line on the downstream side ofthe second bent flow path 540. Actually, a downstream part of thepassage space TS1 e or TS2 e is formed in a state where an outside innerwall surface 57 a or 57 b in the second bent flow path 54C of the blowerduct 51 and an inside inner wall surface 57 c or 57 d that is a portionof the partition wall 55 extends so as to incline inward with respect tothe extension line EL1 or EL2. Additionally, the outside inner wallsurface 57 a or 57 b and the inside inner wall surface 57 c or 57 d thatconstitute the downstream part of the passage space TS1 e or TS2 e, inother words, the extension line thereof is formed in an obliquelyextending manner so as to approach a central extension line OL of thepartition wall 55.

Incidentally, the inside inner wall surface 57 c or 57 d of the passagespace TS1 e or TS2 e is formed by a partition wall increasing portion555 in which the thickness of the partition wall 55 is increasedperpendicularly to the outside inner wall surface of each passage spaceTS1 or TS2 from the midway of the partition wall, and then, is graduallydecreased as it goes to the downstream side in an air flow direction(FIG. 8). Additionally, the height h2 of the downstream opening (theopening portion 53A or 53B of the outlet port) of the passage space TS1e or TS2 e is set to a value that is larger than the height h1 of anupstream opening (h2>h1).

Additionally, the passage space TS1 e or TS2 e, as shown in FIG. 5 orthe like, is set so that the emission direction of air thereof is adirection in which the two corona discharge wires 41A and 41B in thecharging device 4 are not present on an extension line of a centerscheduled line D in the emission direction. Particularly, in ExemplaryEmbodiment 1, the emission direction of the passage space TS1 e or TS2 eis set so as to be a direction in which air runs against the boundaryplate 40 d of the shielding case 40 while avoiding the two coronadischarge wires 41A and 41B in the charging device 4.

The operation of the blowing device 5 will be described below.

If the blowing device 5 arrives at a driving setting timing, such as animage forming operation timing, the blower 50 is first rotationallydriven to send out a required volume of air. The air (E) sent from thestarted blower 50 is taken from each opening portion 52A or 52B thatconstitutes the inlet port 52 of the blower duct 51 through theconnection duct 58 into each passage space TS1 or TS2 that follows theopening portion, in a divided state.

Subsequently, the air (E) taken into the blower duct 51, as shown inFIG. 6 or 9, is sent so as to flow into each passage space TS1 or TS2 ofthe first bent flow path 545 through each passage space TS1 or TS2 ofthe introduction flow path 54A (refer to arrow E1 a or E2 a). The air(arrow E1 a or E2 a) sent into each passage space TS1 or TS2 of thefirst bent flow path 54B passes through the gap 63 of the upstream flowcontrol member 61, and proceeds in a state where the proceedingdirection (direction in which air flows) thereof is changed to an almostright-angled direction.

In this case, the air (E1 a or E2 a) when passing through the gap 63 ofthe first upstream flow control member 61 in each passage space TS1 orTS2 of the first bent flow path 54B has its flow suppressed by passingthrough the narrow gap 63 of the flow control member 61 (the pressure ofthe air is raised), and tends to flow out of the gap 63 in a uniformstate. Moreover, as for the air (E1 a or E2 a) that passes through thegap 63 of the flow control member 61, the direction of the air whenflowing out of the gap 63 is aligned with a direction substantiallyorthogonal to the longitudinal direction (B) of the outlet port 53.

Next, the air (E1 b or E2 b) after passing through the gap 63 of theflow control member 61 in each passage space TS1 or TS2 of the firstbent flow path 54B, moves to each passage space TS1 or TS2 of the secondbent flow path 54C that is continuous in the state of being bent at asubstantially right angle downward from the first bent flow path 54B.

Subsequently, the air (E1 b or E2 b), which has flown into each passagespace TS1 or TS2 of the second bent flow path 54C, flows into eachpassage space TS1 or TS2 of the second bent flow path 54C whose volumeis relatively larger than each passage space TS1 and TS2 of theintroduction flow path 54A or the space of the gap 63 of the flowcontrol member 61, and thereby stagnates temporarily so as to bediffused within each passage space TS1 or TS2 of the second bent flowpath 54C, and the unevenness of the wind speed is reduced.

Lastly, the air (E1 c or E2 c) that has stagnated temporarily in eachpassage space TS1 or TS2 of the second bent flow path 54C, passes thepassage space TS1 e or TS2 e and the opening portion 53A or 53B of theoutlet port that determines the emission direction of air as the mostdownstream flow control member 62 provided in a portion ranging from thedownstream part of the bent flow path 54C to the opening portion 53A or53B that constitutes the outlet port 53, and as shown by arrow E1 d orE2 d in FIG. 9, is emitted to the outside of the blower duct 51 from theopening portion 53A or 53B of the outlet port.

In this case, the air (E1 d or E2 d) emitted from the opening portion53A or 53B of the outlet port 53 passes through the passage space TS1 eor TS2 e with a cross-sectional area that is relatively smaller than thecross-sectional area of the upstream part of each passage space TS1 orTS2 of the second bent flow path 54C, and the opening portion 53A or 53Bof the outlet port, and is sent out in a state where the flow of the airis suppressed (the pressure is raised also at this time). Additionally,the air (E1 d or E2 d) at this time is sent out in a state where theproceeding direction (emission direction) thereof is regulated (guided)to a direction that is slightly directed to the inside from the openingportion 53A or 53B of the outlet port 53.

From the above, the air (E1 d or E2 d) emitted from the blower duct 51is emitted in a substantially equally distributed state from the openingportion 53A or 53B, and is emitted in a state where the wind speedthereof is substantially uniform in the longitudinal direction (B) ofthe opening shape (elongated oblong shape) of the opening portion 53A or53B. Additionally, the air (E1 d or E2 d) at this time is emitted towarda desired direction as described above.

Then, the air (E1 d or E2 d) emitted from the opening portion 53A or 53Bof the outlet port 53 of the blower duct 51 in the blowing device 5 isblown into the internal space (S1 or S2) of the shielding case 40through the opening portion 43 in the top plate 40 a of the shieldingcase 40 of the charging device 4.

In this case, the air (E1 d or E2 d) is emitted at a substantiallyuniform wind speed in the longitudinal direction of the opening portion53A or 53B, and is blown into the internal space (S1 or S2).Additionally, the air (E1 d or E2 d), as shown in FIG. 9, is emittedparticularly through a downstream portion of the passage space TS1 e orTS2 e that determines the emission direction of air, and is therebyblown out so as to run against the boundary plate 40 d of the shieldingcase 40 without strongly hitting the two corona discharge wires 41A and41B in the internal spaces S1 and S2 of the shielding case 40 (FIG. 9).

Thereby, the air (E1 d or E2 d) blown into the internal space (S1 or S2)of the shielding case 40, as illustrated by an arrow E1 e or E2 e inFIG. 9, hits the grid electrode 42 after running against the boundaryplate 40 d, proceeds so that most thereof escapes through the opening ofthe grid electrode 42 or escapes through the gap between a lower endportion in the lateral portion 40 b or 40 c of the shielding case 40 andthe grid electrode 42, and thereby moves so as to be finally emitted tothe outside of the shielding case 40.

As a result, since the air (E1 d or E2 d) emitted from the blower duct51 moves so as to pass by the two corona discharge wires 41A and 41Bwithin the internal spaces (S1 or S2) of the shielding case 40 and isemitted to the outside of the shielding case 40, unnecessary substances,such as discharge products, paper debris, and an external additive oftoner, which are going to adhere to the grid electrode 42 may be keptaway from the two discharge wires 41A and 41B, and may be discharged tothe outside of the shielding case 40. Additionally, since the air (E1 dor E2 d) emitted from the blower duct 51 is not directly and stronglyblown against the two corona discharge wires 41A and 41B, the air doesnot vibrate the corona discharge wires 41A and 41B unnecessarily.

Accordingly, since the charging performance of the charging device 4 maybe kept from deteriorating wholly or partially due to sparse adhesion ofunnecessary substances to the discharge wires 41A and 41B or the gridelectrode 42 and vibration of the discharge wires 41A and 41B, it ispossible to more uniformly charge the peripheral surface of thephotoconductor drum 21. Additionally, a toner image formed in the imageforming unit 20 including the charging device 4, and an image finallyformed on a sheet 9, are excellent images in which the occurrence ofimage defects (uneven density or the like) resulting from chargingdefects, such as uneven charging and deterioration of chargingperformance, is suppressed.

FIG. 10 shows the results of an evaluation test when the performancecharacteristics (wind speed distribution of air emitted from the blowerduct 51) of the blowing device 5 are investigated.

Regarding the test, air with an average air volume of 0.33 m³/min isintroduced from the blower 50, and then, the wind speed (wind speed inthe entire region of each opening portion in the longitudinal directionB) of the air blown out from the opening portion 53A or 53B of theoutlet port 53 of the blower duct 51 is measured. The measurement isperformed by using an air speedometer (F900 made by Cambridge AccuSense,Inc.), and as shown in FIG. 9, moving the air speedometer in thelongitudinal direction B in two locations including the position(pre-position) of the opening portion 53A located on the upstream sidein the rotational direction A of the photoconductor drum 21, and theposition (post-position) of the opening portion 54B located on thedownstream side in the rotational direction A of the photoconductor drum21.

As the blower duct 51, there is used a blower duct in which the overallshape is that as shown in FIGS. 3 to 9, the inlet port 52 is constitutedby the two opening portions 52A and 52B having an oblong opening shapeof 22 mm×11 mm, and the outlet port 53 is constituted by the two openingportions 53A and 53B having an elongated oblong opening shape of 2mm×350 mm. The thickness of the partition wall 55 is 2 mm. The openingportions 53A and 53B have a positional relationship in which the openingportions are apart from each other by 4 mm. Additionally, the upstreamflow control member 61 is configured by arranging a substantiallyflat-plate partition member 64, so that a gap 63, in which the height His 1.5 mm, the path length M is 8 mm, and the width W is 345 mm, ispresent. Moreover, as the passage space TS1 e or TS2 e in the secondbent flow path 54C of the blower duct 51, a passage space is adopted, inwhich the height h1 of the upstream opening thereof is about 10 mm, thepassage length thereof is 10 mm, and the downstream portion thereof isformed in a shape that extends in a direction that inclines inward at anangle of about 30°.

As shown in FIG. 10, the wind speed in the longitudinal direction (B) ofthe two opening portions 53A and 53B that constitute the outlet port 53of the blower duct 51 has a value near about 0.5 to 1.5 m/sec that isthe mean wind speed of a target value substantially over the wholeregion in the longitudinal direction, or a value that is equal to ormore than the above value, and the wind speed in the longitudinaldirection B of the opening portions 53A and 53B is brought into asubstantially uniform state. Additionally, it may be seen that theresults of the respective wind speeds in the opening portion 53A and theopening portion 53B are almost the same value, and thereby, air isemitted in the state of being distributed in substantially equalproportions from the two opening portions 53A and 53B that constitutethe outlet port 53, without being biased to one of the opening portions.Incidentally, in FIG. 10, the left end (0 mm) of the horizontal axis isan end portion near the inlet port 52 out of the outlet port 53 of theblower duct 51.

Here, for reference, a blower duct 520 as a comparative example is shownin FIG. 20.

In a case where the blower duct 520 is compared with the blower duct 51in Exemplary Embodiment 1, the blower duct 520 is different from theblower duct 51 in that the passage space TS of the flow path 54 is notdivided by the partition wall 55, and the most downstream flow controlmember 62 is changed to a state where a permeable member 70 havingplural ventilation portions 71 is installed in the outlet port 53 tobring the outlet port into a closed state, and has the same componentsas those of the blower duct 51 in terms of the other configuration. Inaddition, although there is a difference in that the length of thesecond bent flow path 54C after being bent downward becomes short, thisdifference hardly affects the flow direction and emission method of air(almost the same).

Incidentally, the upstream flow control member 61 has almost the sameconfiguration as the flow control member 61 in Exemplary Embodiment 1.Additionally, the plural ventilation portions 71 in the permeable member70 that constitutes the most downstream flow control member 62 arethrough holes that extend so that each opening shape is substantiallycircular and penetrates in the shape of a straight line. Additionally,the plural ventilation portions 71, for example, are arranged at regularintervals along the longitudinal direction (B) of the opening shape ofthe outlet port 53, and are arranged so as to be present in four rows atthe same intervals as the above regular intervals also in the lateraldirection C orthogonal to the longitudinal direction. Thereby, theplural ventilation holes 71 are formed so as to be dotted throughout thepassage space of the terminating end of the second bent flow path 54C orthe opening shape of the outlet port 53.

Then, the evaluation test of the performance characteristics inExemplary Embodiment 1 is similarly performed using the blower duct 520.The test results are shown in FIG. 21.

The blower duct 520 used in this evaluation test is a blower duct inwhich the inlet port 52 has a substantially square opening shape of 22mm×23 mm, and the outlet port 53 has an oblong opening shape of 17.5mm×350 mm. Additionally, the upstream flow control member 61 isconfigured so that the height H of the gap 63 is about 1.5 mm, the pathlength M is 8 mm, and the width W is 345 mm. Moreover, the mostdownstream flow control member 62 is configured using the permeablemember 70 in which the ventilation holes 71 with a hole diameter of 1 mmand a length of 3 mm are provided under the condition that the densityof the holes is 0.42 pieces/mm² (≅42 pieces/cm²).

FIG. 21A shows test results when air of which the average air volume is0.25 m³/min is introduced from the inlet port 52. In this case, the windspeed of the air (arrow E3) that comes out from the outlet port 53 isbrought into a substantially uniform state in the longitudinal directionB of the opening shape (oblong shape) of the outlet port 53, and isbrought into a substantially uniform state also in the lateral directionC. FIG. 21B shows test results when air of which the average air volumeis 0.33 m³/min is introduced from the inlet port 52. In this case, anuneven (difference) state is brought also in the lateral direction C inaddition to being brought into an uneven state in the longitudinaldirection B of the opening shape of the outlet port 53. As for the windspeed in the lateral direction C, the wind speed on the Post-positionside is increased compared to the wind speed on the Pre-position side.That is, in the blower duct 520, it may be seen that, in a case wherethe air volume of air taken in from the inlet port 52 is increased (forexample, in a case where the air volume is made equal to or more than0.35 m³/min), relatively fast air is emitted from the Post-position sideof the outlet port 53, and the air tends to be biased.

In contrast, in the blower duct 51 related to Exemplary Embodiment 1, asis clear from the results shown in FIG. 10, air of almost the same windspeed is emitted from the two opening portions 53A and 53B thatconstitute the outlet port 53 even in a case where air of which theaverage air volume is 0.33 m³/min is introduced from the inlet port 52.

FIG. 11 shows the results when the emission state of air of the blowerduct 51 related to Exemplary Embodiment 1 to the charging device 4 issimulated. FIG. 11 is a streamline view expressing the state of a mainflow of air when being emitted from the opening portions 53A and 53B ofthe outlet port of the blower duct 51 and blown into the internal spacesof the shielding case 40 of the charging device 4 in lines.Additionally, square shapes in the drawing are virtual frames showingthat the discharge wires 41A and 41B equivalent to actual thickness arepresent at centre positions (points) thereof. In addition, air that isactually flowing is present also at peripheries shown by solid lines.The condition setting of the simulation is performed including theconditions shown in the above evaluation test.

As shown in FIG. 11, according to the blower duct 51 related toExemplary Embodiment 1, when air emitted from the opening portions 53Aand 53B of the outlet port is blown into the internal spaces of theshielding case 40, the air proceeds in the direction in which the aircollides against the boundary plate 40 d, then passes through thevicinities of the discharge wires 41A and 41B (space portions where theboundary plate 40 d is present), passes through space portions below thedischarge wires, and passes through the grid electrode 42 or is emittedto the outside of the shielding case 40 through gaps between lowerportions of the lateral portions of the shielding case 40 and the gridelectrode 42. Additionally, in the blower duct 51, a portion of airblown into the shielding case 40 is circled in the internal spaces (S1or S2) of the shielding case 40 as illustrated by dotted-line arrows inFIG. 11. In any case, in the blower duct 51, air emitted from theopening portions 53A and 53B of the outlet port is not strongly blowndirectly against the two discharge wires 41A and 42B.

Additionally, the results when the emission state of air of the blowerduct 520 related to the above comparative example to the charging device4 is simulated are shown in a streamline view in FIG. 22 for reference.In this case, as for the introduction amount of air from the inlet port52, a case where the average air volume is 0.33 m³/min is set. In theblower duct 520, air emitted from the through holes 71 of the permeablemember 70 that covers the outlet port 53 is blown directly against thetwo discharge wires 41A and 42B. Incidentally, the air blown against thedischarge wire 41B at the Post-position flows so as to pass through aposition (space on the left-hand side of the wire 41B in FIG. 22)slightly shifted from the discharge wire 41B under the influence of anairstream caused by the rotation of the photoconductor drum 21 in thedirection of arrow A. Additionally, although FIG. 22 shows that linesshowing the emission state of air that is simulated from the internalspaces (S1 or S2) of the shielding case 40 to the lower outside arebroken, these broken portions are portions in which the illustration ofthe lines is omitted halfway, and actually, lines that are presentbetween broken upper end portions and lower end portions of the linesare continuous in proximity with each other, similar to the otherstreamline views (FIGS. 11, 14A and 14B, and 16).

Exemplary Embodiment 2

FIGS. 12 and 13 show blower ducts 51B and 51C related to ExemplaryEmbodiment 2.

The blower duct 51B shown in FIG. 12 has the same configuration as theblower duct 51 in Exemplary Embodiment 1 except that the configurationof the most downstream flow control member 62 is changed. In thesubsequent description portions and drawings, common constituentelements are designated by the same reference numerals, and thedescription of the constituent elements is omitted except whennecessary.

That is, the most downstream flow control member 62 in the blower duct51B is configured by forming a passage space TS1 f or TS2 f of astraight-line shape having a smaller cross-sectional area than thecross-sectional area of each passage space TS1 or TS2 of the second bentflow path 54C. The passage space TS1 f or TS2 f is formed in a shapethat extends linearly so that the overall passage thereof is parallel tothe extension line (EL1, EL2: refer to FIG. 8) along the outside innerwall surface of the part of each passage space TS1 or TS2 of a form thatextends substantially in the shape of a straight line on the downstreamside of the second bent flow path 54C.

Incidentally, the inside inner wall surface (57 c, 57 d: refer to FIG.8) of the passage space TS1 f or TS2 f, substantially similar to thecase of the passage space TS1 e or TS2 e in Exemplary Embodiment 1, isformed by a partition wall increasing portion 55C of a form in which thethickness of the partition wall 55 is increased so as to be orthogonalto the outside inner wall surface of each passage space TS1 or TS2 fromthe midway of the partition wall, and then is continuous with the sameincreasing amount to the downstream side in the air flow direction.Additionally, the height h3 of the downstream opening (the openingportion 53A or 53B of the outlet port) of the passage space TS1 f or TS2f is set to a value that is the same as the height of the upstreamopening.

Additionally, the passage space TS1 f or TS2 f is set so that theemission direction of air thereof is a direction in which the two coronadischarge wires 41A and 41B in the charging device 4 are not present onthe extension line of the center scheduled line D (FIG. 14A) in theemission direction. Specifically, the passage spaces are set indirections that pass through the insides of the two discharge wires 41Aand 41B. The opening portion 53A or 53B of the outlet port that is atermination end of the passage space TS1 f or TS2 f is an elongatedoblong shape whose opening shape is parallel to the longitudinaldirection B of the charging device 4, and both the opening portions areset at positions apart from each other by a distance K1 (for example, 10mm).

The blower duct 51C shown in FIG. 13 has the same configuration as theblower duct 51B shown in FIG. 12 except that a change is made in whichthat the interval K2 between the passage spaces TS1 f and TS2 f thatconstitute the most downstream flow control member 62 is narrowed. Thatis, in the blower duct 51C, the interval K2 between the passage spacesTS1 f and TS2 f is set to a value (K2<K1: for example, 3 mm) that issmaller than the interval K1 in the blower duct 51B shown in FIG. 12.

FIGS. 14A and 14B show the results when the emission state of air of theblower ducts 51B and 51C related to Exemplary Embodiment 2 to thecharging device 4 is simulated. In this simulation, the conditionsetting of the passage spaces TS1 f and TS2 f in the second bent flowpath 54C is the same condition setting of the simulation in ExemplaryEmbodiment 1 except that the height h3 of the overall passage is 2 mm,the passage length is 15 mm, and the interval K1 between the passagespaces TS1 f and TS2 f is 10 mm, and the interval K2 is 3 mm.

In the case of the blower duct 51B, as shown in FIG. 14A, when airemitted from the opening portions 53A and 53B of the outlet port isblown into the internal spaces of the shielding case 40, the airproceeds in a meandering manner so as to be curved to the sideapproaching the boundary plate 40 d rather than proceeding linearlyalong the linear directions of the passage spaces TS1 f and TS2 f(center scheduled lines D), then passes through the vicinities of thedischarge wires 41A and 41B (space portions where the boundary plate 40d is present), passes through space portions below the discharge wires,and passes through the grid electrode 42 or is emitted to the outside ofthe shielding case 40 through gaps between lower portions of the lateralportions of the shielding case 40 and the grid electrode 42. For thisreason, also in the blower duct 51B, air emitted from the openingportions 53A and 53B of the outlet port is barely blown strongly anddirectly against the two discharge wires 41A and 42B. In addition, it isinferred that the phenomenon in which the air emitted from the openingportions 53A and 53B of the outlet port in the blower duct 51B does notproceed linearly along the linear directions (center scheduled lines D)of the passage spaces TS1 f and TS2 f but proceeds in a meanderingmanner to the side approaching the boundary plate 40 d is, for example,influenced by the uneven distribution of pressure caused by the rotationof the photoconductor drum 21, the uneven distribution of the wholeinternal pressure of the housing 10 caused by component parts (devices)arranged around the charging device 4, or the like.

In the case of the blower duct 51C, as shown in FIG. 14 b, when airemitted from the opening portions 53A and 53B of the outlet port isblown into the internal spaces of the shielding case 40, the airproceeds linearly in a state where the air has approached the boundaryplate 40 d, then passes through the vicinities of the discharge wires41A and 41B (space portions where the boundary plate 40 d is present),passes through space portions below the discharge wires, and passesthrough the grid electrode 42 or is emitted to the outside of theshielding case 40 through gaps between lower portions of the lateralportions of the shielding case 40 and the grid electrode 42. For thisreason, also in the blower duct 51C, air emitted from the openingportions 53A and 53B of the outlet port is barely blown strongly anddirectly against the two discharge wires 41A and 42B.

Exemplary Embodiment 3

FIG. 15 shows a blower duct 51D related to Exemplary Embodiment 3.

The blower duct 51D has the same configuration as the blower duct 51 inExemplary Embodiment 1 except that the configuration of the mostdownstream flow control member 62 is changed.

That is, the most downstream flow control member 62 in the blower duct51D is configured by forming a passage space TS1 g or TS2 g in a shapehaving a smaller cross-sectional area than the cross-sectional area ofeach passage space TS1 or TS2 of the second bent flow path 54C and in ashape that is bent so that the air flow direction is directed outward onthe downstream side. The passage space TS1 g or TS2 g is formed in ashape that extends in a straight line so that an upstream part thereofis parallel to the extension line (EL1, EL2: refer to FIG. 8) along theoutside inner wall surface of the part of each passage space TS1 or TS2of a form that extends substantially in the shape of a straight line onthe downstream side of the second bent flow path 54C, and so that adownstream part thereof is formed in a shape that is bent so as togradually approach the extension line along the outside inner wallsurface of the each passage space TS1 or TS2.

Incidentally, the height h4 of the downstream opening (a part that isthe opening portion 53A or 53B of the outlet port) of the passage spaceTS1 g or TS2 g is set to a value that is the same as the height of theupstream opening. Additionally, the passage space TS1 g or TS2 g is setso that the emission direction of air thereof is a direction in whichthe two corona discharge wires 41A and 41B in the charging device 4 arenot present on the extension line of the center scheduled line D (FIGS.15A and 15B) in the emission direction. Specifically, the passage spacesare set in directions that pass through the outsides of the twodischarge wires 41A and 41B (refer to the flows of air of FIG. 16).

FIG. 16 shows the results when the emission state of air of the blowerduct 51D related to Exemplary Embodiment 3 to the charging device 4 issimulated. In this simulation, the condition setting of the passagespaces TS1 g and TS2 g in the second bent flow path 54C is the samecondition setting of the simulation in Exemplary Embodiment 1 exceptthat the height h4 of the overall passage is 2 mm, the passage length is15 mm, and the passage spaces TS1 g and TS2 g are directed outward at anangle (elevation angle) of about 30° with respect to the centerline ofthe partition wall 55.

In the case of the blower duct 51C, as shown in FIG. 16, when airemitted from the opening portions 53A and 53B of the outlet port isblown into the internal spaces of the shielding case 40, the air passesthrough the vicinities of the discharge wires 41A and 41B (spaceportions where the boundary plate 40 d is not present), and passesthrough the grid electrode 42 or is emitted to the outside of theshielding case 40 through gaps between lower portions of the lateralportions of the shielding case 40 and the grid electrode 42. For thisreason, also in the blower duct 51D, air emitted from the openingportions 53A and 53B of the outlet port is barely blown strongly anddirectly against the two discharge wires 41A and 41B.

Exemplary Embodiment 4

FIG. 17 shows a blower duct 51E related to Exemplary Embodiment 4.

The blower duct 51E has the same configuration as the blower duct 51 inExemplary Embodiment 1 except that the configuration of the mostdownstream flow control member 62 is changed.

That is, as shown in FIGS. 17 and 18, the most downstream flow controlmember 62 in the blower duct 51E is configured by installing thepermeable member 70 having the plural ventilation portions 71 in eachopening portion 53A or 53B of the outlet port of a shape that has thesame cross-sectional area as the cross-sectional area of each passagespace TS1 or TS2 of the second bent flow path 54C and bringing theopening portion into a closed state.

The plural ventilation portions 71 in the permeable member 70 thatconstitutes the most downstream flow control member 62 are through holesthat extend so that each opening shape is substantially circular andpenetrate in the shape of a straight line, as described as a portion ofthe configuration of the blower duct 520 of the comparative example.Additionally, the plural ventilation portions 71, for example, arearranged at regular intervals along the longitudinal direction (B) ofthe opening shape including the elongated oblong shape of the openingportion 53A or 533 of the outlet port, and are arranged so as to bepresent in plural rows at the same intervals as the above regularintervals also in the lateral direction C orthogonal to the longitudinaldirection. Thereby, the plural ventilation holes 71 are formed so as tobe dotted throughout the passage space of the terminating end of thesecond bent flow path 54C or each opening portion 53A or 533 of theoutlet port. Moreover, it is preferable that the plural ventilationportions 71 be formed so as to be dotted substantially uniformly (in asubstantially constant density) in each opening portion 53A or 53B ofthe outlet port. However, unless the air that comes out from eachopening portion 53A or 53B comes out non-uniformly, the ventilationportions may be formed so as to be present in a slightly dense state.

The permeable member 70 in Exemplary Embodiment 4 is a perforated platethat is formed so that the plural ventilation portions (holes) 71 aredotted in a plate-shaped member. The permeable member 70 is formed bybeing integrally molded from the same material as the blower duct 51E oris formed from a material separate from the blower duct 51E and mountedon each opening portion 53A or 53B of the outlet port. The openingshape, opening dimension, hole length, and hole presence density of theventilation portions (holes) 71 are selected and set from a viewpoint ofmaking the wind speed of air that has flown out of the second bent flowpath 54C through each opening portion 53A or 53B of the outlet port asuniform as possible, and are set in consideration of the dimension(capacity) of the blower duct 51E, the flow rate per unit time of aircaused to flow to the blower duct 51E, the charging device 4, or thelike.

The blowing device 5 to which the blower duct 51E is applied operates asfollows.

The air (E) taken in from the blower 50 flows into the second bent flowpath 54C after passing through the introduction flow path 54A, and thefirst bent flow path 54B provided with the upstream flow control member61 sequentially, similar to the case of the blower duct 51 related toExemplary Embodiment 1. Subsequently, in the blower duct 51E,particularly, the air that has flown into and stagnated in the secondbent flow path 54C passes through the plural ventilation portions(holes) 71 in the permeable member 70 that constitutes the mostdownstream flow control member 62 provided in each opening portion 53Aor 53B of the outlet port, and is thereby blown out from each openingportion 53A or 53B in a state where the proceeding direction thereof ischanged.

In this case, the air blown out from each opening portion 53A or 53B ofthe outlet port passes through the plural ventilation portions 71 of thepermeable member 70 that is relatively narrower than the originalopening area (the total cross-sectional area of the passage spaces TS1and TS2 of the second bent flow path 54C) of the outlet port 53, and isthereby sent out in a state where the flow thereof is suppressed (atthis time, the pressure of the air is raised). Additionally, the airblown out from each opening portion 53A or 53B of the outlet port passesthrough the plural ventilation portions 71 that are dotted throughouteach opening portion 53A or 53B of the outlet port and formed on thesame conditions, whereby the air is sent out in a uniform state so as tobe equivalent to the surface (elongated oblong shape) of a regionsubstantially similar to the opening shape of each opening portion 53Aor 53B. Moreover, the air blown out from each opening portion 53A or 53Bof the outlet port has its proceeding direction changed to the directionsubstantially orthogonal to the longitudinal direction of each openingportion 53A or 53B of the outlet port, and is sent out.

From the above, the air emitted from the plural ventilation portion 71of the permeable member 70 in each opening portions 53A or 53B of theoutlet port is emitted in a substantially equally distributed state fromeach opening portion 53A or 53B, and is emitted in a state where thewind speed thereof is substantially uniform in the longitudinaldirection (B) of the opening shape (elongated oblong shape) of theopening portion 53A or 53B. Additionally, the wind speed of the air thatcomes out from each opening portion 53A or 53B is brought into asubstantially uniform state in the longitudinal direction (B) of theopening shape of each opening portion 53A or 53B as described above, andis brought into a substantially uniform state also in the lateraldirection C.

Then, the air sent out from each opening portion 53A or 53B of theoutlet port of the blower duct 51E is exclusively blown into theinternal space S1 or S2 from the top opening portion 43 of the shieldingcase 40 of the charging device 4, comes into contact with the gridelectrode 42 while passing through each of the two corona dischargewires 41A and 41B in each internal spaces S1 or S2, proceeds so as toescape through the gap between the lower end portion in the lateralportion 40 b or 40 c of the shielding case 40 and the grid electrode 42,and finally moves so as to be emitted to the outside of the shieldingcase 40.

In this case, the air that passes through the internal space S1 or S2proceeds so as to flow in a substantially uniform state in thelongitudinal direction (B) of the internal space, and proceeds so as toflow in a substantially uniform state also in the lateral direction C.Thereby, unnecessary substances, such as a discharge product, paperdebris, an additive agent of toner, which are going to adhere to the twodischarge wires 41A and 41B and the grid electrode 42, may be kept awaywithout the unevenness, and may be discharged to the outside of theshielding case 40.

Other Exemplary Embodiments

As the flow path 64, the flow paths that have the passage space ST1 andST2 that are divided into two by the partition wall 55 are illustratedin Exemplary Embodiments 1 to 4. However, a flow path 64 that has threeor more passage spaces ST that are divided by plural partition walls 55may be applied.

Additionally, although the cases where the two flow control members 61and 62 are provided as the flow control members in the blower duct 51are shown in Exemplary Embodiments 1 to 4, three or more flow controlmembers may be provided. Additionally, it is preferable to provide allthe flow control members which also includes the most downstream flowcontrol member in a part whose cross-sectional shape is changed in thepassage space TS of the flow path 54 of the duct 51 or in a part after(immediately after or the like) the air flow direction in the passagespace TS is changed.

The case where the most downstream flow control member 62 is configuredusing the permeable member 70 formed so that the plural ventilationportions (holes) 71 are substantially uniformly dotted throughout eachopening portion 53A or 53B of the outlet port is illustrated inExemplary Embodiment 4. However, in addition to this, the mostdownstream flow control member may also be configured using thepermeable member 70 represented by, for example, porous members (inwhich the plural ventilation portions 71 are irregular through-gaps),such as a nonwoven fabric applied to filters.

In addition, the blower duct 51 is not limited to the case where theoverall shape is illustrated in Exemplary Embodiment 1, and blower ductshaving other shapes may be applied. For example, the blower ducts 510(510A to 510D) illustrated in FIGS. 19A to 19D may also be applied.

Additionally, the charging device 4 to which the blowing device 5 isapplied may be a charging device of a type in which the grid electrode24 is not installed, that is, a so-called corotron type charging device.The charging device 4 may be a charging device using one coronadischarge wire 41 or three or more corona discharge wires. Additionally,as the elongated target structure to which the blowing device 5 isapplied, a corona discharger that performs neutralization of thephotoconductor drum 21 or the like, or a corona discharger that chargesor neutralizes members to be charged other than the photoconductor drummay be used. In addition, an elongated structure, in which pluralportions against which air are to be blown are present along thelongitudinal direction, other than the corona discharger may be used.

Moreover, the configuration of an image forming method or the like isnot particularly limited if the image forming apparatus 1 includes anelongated target structure that needs to apply the blowing device 5 toblow air. If necessary, an image forming apparatus that forms an imageformed from materials other than developer may be used.

The foregoing description of the exemplary embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to practitioners skilled in the art. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with the various modifications as are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

What is claimed is:
 1. A blower pipe comprising: an inlet port thattakes in air; an outlet port that has an elongated opening shape that isparallel to a portion of an elongated target structure in a longitudinaldirection and that is arranged so as to face the portion of theelongated target structure in the longitudinal direction against whichthe air taken in from the inlet port is to be blown and is differentfrom the opening shape of the inlet port; a flow path that connects theinlet port and the outlet port to cause air to flow therethrough andthat are divided by a partition wall, the partition wall beingcontinuously provided from the inlet port to the outlet port and theflow path having a bent portion which bends flow direction substantiallyat a right angle; and a plurality of flow control members that arerespectively provided in different parts in an air flow direction ineach of divided passage spaces that are divided by the partition walland that control the flow of the air, wherein the inlet port and theoutlet port are constituted by a plurality of opening portions that aredivided by the partition wall, respectively, wherein the plurality ofopening portions that constitute the outlet port have elongated openingshapes that are divided by the partition wall in a state where theelongated opening shape of the outlet port is parallel to thelongitudinal direction of the target structure, and wherein a flowcontrol member of the plurality of flow control members closest to theinlet port is provided in the vicinity of the bent portion, which makesa portion of each of the flow path narrower than other portion of eachof the flow path and makes an elongated gap extending in thelongitudinal direction to pass air, wherein a portion of the partitionwall between the inlet port and the bent portion is substantiallyparallel to both an air flow direction at the inlet port and an air flowdirection bent by the bent portion.
 2. The blower pipe according toclaim 1, wherein a flow control member closest to the outlet port amongthe plurality of flow control members is formed such that each openingportion has a smaller cross-sectional area than the cross-sectional areaof each of the passage spaces.
 3. The blower pipe according to claim 2,wherein the flow control member closest to the outlet port bends each ofthe air flow direction.
 4. The blower pipe according to claim 1, whereinthe target structure is a corona discharger including at least asurrounding member that has an elongated internal space along thelongitudinal direction and is formed with a discharging opening portionand an air introduction opening portion, and a plurality of dischargewires that are stretched in parallel along the longitudinal directionwithin the internal space of the surrounding member.
 5. The blower pipeaccording to claim 4, wherein the opening portion of the outlet port ofeach of the passage spaces is formed so that a direction in which air isemitted is a direction in which the discharge wires of the coronadischarger are not present on an extension line of a centerline of thedirection which air is emitted.
 6. The blower pipe according to claim 4,wherein the corona discharger includes a boundary plate that is arrangedso as to be interposed between the a plurality of discharge wires withinthe internal space of the surrounding member to divide the internalspace, and wherein the opening portion of the outlet port of each of thepassage spaces is formed so that a direction in which air is emitted isa direction in which air runs against the boundary plate of the coronadischarger while avoiding the plurality of discharge wires.
 7. A blowingdevice comprising: a blower that sends air; and the blower pipeaccording to claim 1, wherein the air sent from the blower is taken infrom each of the opening portions of the inlet port of the blower pipe.8. The blowing device according to claim 7, wherein the target structureis a corona discharger including at least a surrounding member that hasan elongated internal space along the longitudinal direction and isformed with a discharging opening portion and an air introductionopening portion, and a plurality of discharge wires that are stretchedin parallel along the longitudinal direction within the internal spaceof the surrounding member.
 9. An image forming apparatus comprising: anelongated target structure against which air is to be blown; and ablowing device that blows air toward a portion of the target structurein the longitudinal direction, wherein the blowing device is the blowingdevice according to claim
 7. 10. The image forming apparatus accordingto claim 9, wherein the target structure is a corona dischargerincluding at least a surrounding member that has an elongated internalspace along the longitudinal direction and is formed with a dischargingopening portion and an air introduction opening portion, and a pluralityof discharge wires that are stretched in parallel along the longitudinaldirection within the internal space of the surrounding member.
 11. Theblower pipe according to claim 1, wherein the flow path has a secondbent portion which bends flow direction and is provided on downstream ofthe bent portion, and wherein the partition wall bends according to thesecond bent portion.
 12. A blower pipe comprising: an inlet port thattakes in air; an outlet port that has an elongated opening shape that isparallel to a portion of an elongated target structure in a longitudinaldirection and that is arranged so as to face the portion of theelongated target structure in the longitudinal direction against whichthe air taken in from the inlet port is to be blown and is differentfrom the opening shape of the inlet port; a flow path that connects theinlet port and the outlet port to cause air to flow therethrough andthat are divided by a partition wall, the partition wall beingcontinuously provided from the inlet port to the outlet port and theflow path having a bent portion which bends flow direction substantiallyat a right angle; a plurality of flow control members that arerespectively provided in different parts in an air flow direction ineach of divided passage spaces that are divided by the partition walland that control the flow of the air; and a permeable member having aplurality of ventilation portions and provided in the opening portion ofthe outlet port, wherein the inlet port and the outlet port areconstituted by a plurality of opening portions that are divided by thepartition wall, respectively, and wherein the plurality of openingportions that constitute the outlet port have elongated opening shapesthat are divided by the partition wall in a state where the elongatedopening shape of the outlet port is parallel to the longitudinaldirection of the target structure, wherein a flow control member of theplurality of flow control members closest to the inlet port is providedin the vicinity of the bent portion, which makes a portion of each ofthe flow path narrower than other portion of each of the flow path andmakes an elongated gap extending in the longitudinal direction to passair, and wherein the opening portion is closed by the permeable member.